1. Field of the Invention
This invention relates to electronic apparatus for selectively performing different operations in response to actuation of keys on a keyboard.
2. Description of the Prior Art
Many types of electronic apparatus are operated by selective actuation of push buttons or touch operated keys on a keyboard panel to perform a variety of operations. One example of such an electronic apparatus is a telephone, which dials different numbers in response to actuation of correspondingly numbered keys. Another example is a radio, which is tuned to different broadcast stations in response to information entered by actuating the various keys. In fact, almost all types of electronic apparatus which perform at least two distinct operations will generally have some form of keyboard panel through which the operator's selection may be entered.
Customarily, each key on the keyboard bears an indication of the corresponding operation to inform the operator of what will occur upon actuation of that key. For example, each key on the telephone keyboard bears the number corresponding to the digit dialled in response to actuation. In a radio, some keys may bear the number of a memory location containing the frequency to which the radio will be tuned upon actuation, or a key may bear an arrow indicating a frequency scanning direction.
It is now possible to have a variety of such electronic apparatus installed in the dashboard of an automobile for operation by the driver. It is essential for safe driving that the driver be able to keep his eyes on the road, while at the same time selecting the appropriate key. Therefore, a keyboard device has been proposed in which the top of each key has a differently shaped convex surface, identifiable by touch, so that the driver can identify each key without looking at it. Unfortunately, this still requires a degree of concentration which is distracting, and this type of keyboard device is frequently misoperated.
A second type of keyboard device has been proposed in which a different beep tone is generated in response to actuation of each key to identify the operation. A variation thereof has the actuated key being lit up. However, the different beeps/lights are generated only after actuation, that is, after performance of the operation, and serve only to identify which operation has been performed. This keyboard device does not aid the operator in deciding beforehand which key to actuate, and so does not aid in avoiding misoperation.